Insects in winter: Metabolism and regulation of cold hardiness
Insects are found in most of coldest places on Earth-the Arctic, the Antarctic, high on mountains. Many temperate and polar species display outstanding tolerances of cold temperatures and have amazing survival stories. For example, the Arctic Woolly Bear moth (Gynaephora groenlandica) is a caterpillar for seven years, feeds for only one month each summer, spends most of its life frozen, and endures temperatures as low as -70°C (Morewood et al. 1998). Insect cold hardiness is widely studied not only to understand the diversity and mechanisms of adaptations that contribute to survival below 0°C but also for applied purposes in agriculture and forestry to analyze (and possibly manipulate) the cold hardiness of beneficial or pest species. Not surprisingly, several main models for insect cold hardiness research are economically important pests including the rice stem borer (Chilo suppressalis), onion maggot (Delia antiqua), and spruce budworm (Choristoneura fumiferana).